As Long As You Stand By Me
by ResidentBunburyist
Summary: He'll wear his promise to Mary on his left hand and his promise to Sherlock on his right. And if John Watson is anything, he is a man of his word.


_**Apologies in advance for lack of Brit-picking.**_

After careful consideration, and having examined all circumstantial evidence from every possible angle, Sherlock can come to only one conclusion:

John is an idiot.

John is a compulsive, romantically addled idiot, and he's going to ruin everything.

He's had plenty of time to work this over properly in his head, too. Because John is currently on the fourth consecutive day of not speaking to him.

Or perhaps he's not speaking to John? It's a bit difficult to discern at this point who's stubbornness is prolonging the angry silence that hangs thick over 221b.

John definitely started it though. Of course, if asked, he'll say differently- probably spout something about how Sherlock _overreacted_ or some such nonsense. Which is ridiculous. _Sherlock _isn't the one who came home on Tuesday morning to declare that he is about to make what Sherlock is quite certain is going to be the biggest mistake of his life.

And then he expected Sherlock to be _happy_ for him.

It doesn't make any sense. How could John expect him to be happy that he's throwing his life of following Sherlock on his cases and adventures- hadn't John wanted adventure at some point?- away in favor of a boring domestic existence with a _wife_ and a _steady job_ and all of those other terribly average things that make Sherlock's skin crawl-

Oh god, kids. John's probably going to have kids now.

What? No, John hasn't said quite that much yet, but that hardly matters. It's perfectly obvious. Logical progression and all that. It's been obvious since the moment that damned Morstan woman had sat on their couch, big doe eyes filled to the brim with tears she was too proud to shed, asking for Sherlock's help. He'd taken the case, too. Even waived the fee, which rather irks him in hindsight. Not that he cares about the money at all, but it would have been nice to inconvenience her _somehow._ For all intents and purposes, he'd introduced them, so it's really his own fault in the end. He could have taken it upon himself to comfort her in her grief over her father's disappearance (or better yet, just left her to stew in her own misery- her happiness, or lack thereof, was not going to affect the outcome of the case) but it had just been so much _easier_ to let John do it. And if she decided to latch... well, it was a mild nuisance, but one that usually resolved itself by the third or fourth time John stood up a date to join Sherlock on a case.

But latch she had, and with quite the grip. He had rarely felt the need to actively push away John's girlfriends (frankly, John was more than adept at accomplishing that himself) but Mary was just so... so damned _understanding_! No matter how often John canceled on her to join Sherlock, she'd just smiled and let him go, promising to have food ready for him when he got back, like some doting little housewife. Food! He and _Sherlock_ went out for food after a case! Mary did not fit into this equation!

And of course John found her engaging and funny and all of those trite things that girlfriends were supposed to be, and no amount of disparaging comments on Sherlock's part about her boring dead-end job or her awful taste in media or even her demonic excuse for a dog could turn John away from her.

Indeed, when he had finally been forced towards sabotage, the only thing more impressive than his efforts were Mary's tenacity to weather them. (Even he'll admit that the incident with the fetal pigs might have been overkill. But only after John punched him solidly in the face for it.) In fact, and quite inexplicably, Mary seemed to even _like _Sherlock. To some degree at least. Enough so that it appeased John. (Why it mattered to John whether or not his girlfriends liked Sherlock was one of those baffling aspects about his friend that he'd never quite understand.)

And then he had come home on Tuesday morning, a stupid grin shining across his face like he'd accomplished something terribly clever, the only thing missing from his person the ring-box which he had stowed into his pocket the previous night. (He hadn't thought that Sherlock knew about it. Which was, and always is, a preposterous assumption. When will John just learn to assume that Sherlock knows everything until proven otherwise?) Sherlock hadn't waited for him to tell him the 'good news.'

"Don't expect me to congratulate you." He offered the moment his (now temporary) flatmate had crossed the threshold. He had been aiming for a bored drawl, to show just how little John's blunder in judgment affected him, but ultimately failed to keep the biting anger out of his voice.

The smile faltered. "What?"

"You proposed last night, she said yes, and you came running to tell me about it as soon as possible. Well, don't bother. I want nothing to do with any of it- and before you ask, no, I am not going to be the best man at the wedding, so forget it. Go ask Lestrade or Mike or someone who cares enough to pretend to be happy for your stupidity. I am far too busy for such tedium." He had managed to throw himself in a suitably languid position on the sofa right before John came home, so John never really needs to know that 'busy' consisted largely of pacing a groove into the floor for a solid nine hours waiting for him to return.

John blinked, processing Sherlock's tirade, the beginnings of various emotions flitting across his face- incredulity, then anger, then something simmering dangerously close to disappointment.

"Right." he said at last, the word strangled and short in his throat. He stood in the doorway, shifting from one foot to the other, trying to find his balance in a conversation that he had obviously hoped would play out differently. "Right. I... you know what, my fault. I shouldn't have expected you to act any differently. I shouldn't have expected you to actually support me." Oh, yes, so much disappointment just dripping from his words, congealing in his clenched hands and stiff back.

Sherlock bristled. "No, you shouldn't have." How _dare _John try to guilt him? How dare he act like Sherlock was the one in the wrong, as if he were the one upending their entire way of life on what Sherlock could only discern was a ridiculous whim? No, John Watson could take his empathy and kindly shove it, because it wasn't going to work this time. "Glad you could figure that out for yourself. Now go cry about it to Meghan and kindly _leave me alone._"

"It's Mary." John said through clenched teeth.

Sherlock's lip twisted in distaste. "Whatever."

"Why do you hate her so much?" John demanded.

"Why do you you care?" Sherlock countered, voice rising in volume to meet John's. "It obviously doesn't matter what I think, because you're marrying her anyway."

"Yeah, but it would be nice to know that my best friend approves of one of the most important decisions of my life!"

"Well, for all that it's worth, your best friend doesn't. I suggest you either deal with it or find yourself a better best friend. Or better yet, call all of this off before you inevitably regret it."

That was the beginning of the four days of John refusing to look at him, of ignoring him when he went out to follow a fresh lead, of pointedly making only one cup of tea in the morning. (Sherlock hasn't had a cup of tea in four days and eight hours. That is approximately four days and seven hours longer than he'd like to go without a cup of tea. He _could_ get once himself, but that would be admitting that John's won by forcing Sherlock to alter _his _routine for _John's_ petulance. And that's not going to happen.)

So now Sherlock's sitting in the kitchen, staring sullenly into the clear contents of a glass beaker. He adds another drop of potassium chlorate, ignoring the angry shake in his hands as comes to that decision that John is, in fact, an idiot. (That, or his hands might just be shaking from hunger. He hasn't really had the motivation to feed himself properly over the past few days. Making sure he eats is John's job. Most matters of Sherlock's personal health are John's job.)

John's still up, despite the late hour. Sherlock can hear the slow rattle of John's fingers pecking inexpertly at the computer. He's been typing for the better part of an hour now, so is almost certainly writing up a new case. Probably the first draft of the Croyden case. His fingers tighten around the beaker as he thinks about his flatmate (should learn to stop calling him that, he's not going to be his flatmate for much longer) typing up a case as usual, as if nothing's changed at all. Stupid.

But really, that's the rub, isn't it? John's not the one being stupid. Sherlock is. John hasn't broken any sort of contract or anything. The deal had been to share a flat because the both of them were hurting for money. (Well, John was at least. Sherlock _had_ the money, but a certain meddling brother had cut him off of it before he "snorted it all away." Which was entirely wrong. He injected.) That they had become friends had merely been a bonus.

That they had become inseparable had been entirely unexpected.

That Sherlock had somehow in the past few years become so reliant upon John's presence that he can't get himself a cup of tea if John's not talking to him is... a hindrance, really. He never meant to get so attached! It just happened. When his guard was let down John Watson had wormed his way into Sherlock's life and settled in so thoroughly that Sherlock can no longer imagine living without him.

Except that he's going to have to now. At some point he had become entirely complacent, even expectant, with the notion that John would stick around forever. And now John's just up and leaving. (Would it be melodramatic to say 'abandoning?' Perhaps so. But it certainly feels like the right verb. Yes, 'abandoning' will do nicely.)

John will have a nice place with his nice wife, and of course he'll try to stay in touch, at least at first. That's the boon of today's technology, isn't it? In theory, John will never be more than a phone call or quick e-mail away.

But that's not enough, it's not nearly enough. He'll start denying cases. He'll settle in with Morgan or Maggie or whatever her name is. (Okay, it's Mary and he knows it. He'll admit in his head, at least, that of course he remembers the name of the person who's going to rip him apart from his best- truly, his only- friend in the world. The name Mary Morstan is a curse on his lips.)

It won't take long for the correspondence to dwindle. Sherlock can't be bothered to 'meet for drinks' or 'catch up,' not even with John. If John's not a part of his work, John's not a part of his life. No, their contact will decrease until it is nothing more than a card on holidays, a quick text on hastily-remembered birthdays. A name dropped at social gatherings- "yes, Sherlock Holmes, I once knew him, if you could believe that. No idea what's happened to him. More coffee?"

He's seen it before, observed it in others- friendships that die slowly, when there's nothing to keep them alight. And it will hurt so much more than losing them quickly in one solid, damning blow, like ripping a plaster (or estranging himself from Victor Trevor.) It'll be a slow, inevitable process, like watching a loved one wilt away slowly of an illness, knowing that there's nothing that can be done to reverse the process, until the withered husk is one of a person barely recognizable. People drift from one another, and as suddenly as he realized one day that John Watson is and indispensable aspect of his life, he'll wake up one morning and realize that he was wrong all along, and that he barely remembers the man he shared a life with all those years ago.

He's barely paying any attention to the solution in his beaker. Another few drops of chlorate, and the mixture (already much hotter than it should be) hisses angrily. The glass suddenly shatters, and he yelps as a stabbing pain shoots through his right hand.

Fuck! Just! Fuck everything. _This _is why he doesn't do anything when he's busy brooding. Science needs _concentration _and dammit, he _would_ have just taken the sofa for a nice long sulk, but John is still out there and he just _doesn't_ want to see John acting like he always has, like he isn't going to leave forever, and-

"Sherlock! Sherlock, are you okay? I heard shouting." Dammit. Okay, John is now in here. Staring at him. Go _away_, John! If he's got to start forgetting you, he might as well do it now. Like a plaster, not a cancer patient. Rip it in one go.

John's face is concerned, open. Actually looking at him for the first time in four days. "You're bleeding. I'll get the med kit."

"I'm fine." Leave him _alone_ John! He's coped for a good thirty-some years without your help, he can do it again! Go back to ignoring him, that was working well, wasn't it?

He pulls a piece of glass out of his palm with a small hiss. Blood flows freely down his wrist, dripping onto the table. Damn it all, that was a new beaker, too.

The cut looks clean, though, and not too deep. Hopefully it won't need stitches. He holds it under the tap, wincing slightly as the water runs over it, swirling red in the bottom of the sink.

John reappears at the table and opens the med kit. "Let me see it."

"I said I'm fine." He shoulders past John and starts digging in the kit one-handed.

"Sherlock, let me see it." John's tone is low and patient. He tries to grab Sherlock by the wrist. Sherlock jerks back.

"Leave it alone!" He snarls. He can do it on his own_._ He's perfectly self-sufficient. He doesn't need help, or flatmates, or _friends._

"I'm trying to help you!"

"_I don't need you!_"

There. He's said it. Right to John's face. Even he's not dense enough to misunderstand that. He doesn't need John- not to help him with injuries, not to get him tea, not for companionship. He doesn't need him.

He expects John to get back up. Give him that exasperated, hurt look he's been so fond of as of late. Go back to ignoring him. Sherlock glares down at the med kit and holds his breath. Don't make this harder than it has to be, John. Just go. Please. Just go.

But when John responds, his voice is strangely light. "You moron..." he whispers, half to himself. Sherlock's eyes shoot up. John's eyes are soft, and the corner of his mouth is lifted into something almost affectionate. "Jesus, Sherlock, for having the world's biggest ego, you're damned insecure sometimes, you know that?"

Sherlock's scowl deepens. He pulls his right hand closer to his chest, cradling it in his left. It's dripping onto his shirt now, but he doesn't care.

John sighs, and drops into the empty chair beside him. Sherlock narrows his eyes warily, but says nothing. Wants to see what John has to say. That outburst should have sent him from the room, enraged and upset. But the emotions playing across his face are all wrong.

Eyes are no longer on Sherlock's face- they're locked somewhere around his collar. But his shoulders are relaxed enough to say that it's not due to anger that he's not looking at Sherlock. Uncomfortable, but determined. He takes a deep breath. Opens his mouth, and then closes it again. Obviously trying to decide how to proceed.

"I love Mary. Really, I do." he starts. "She's kind, she's clever-"

"Are you just going to gush about your girlfriend?"

"Fiancee." John corrects. "Now shut up and listen. She's wonderful, but so are a lot of other women. The reason why she and I work together so well is because she understands something that you clearly don't."

"That you have a hidden desire for a boring existence?"

"No. That I have a hidden need for a lively one." He looks back up at Sherlock. "Mary understands, Sherlock, that I can't just sit back and have an average life. I'll go mad. I tried, back when you..." He falters for a moment. Blinks hard. It's still apparently painful for him to think about Sherlock's 'death,' even though it was fake. For three years, it was terribly, terribly real. "Back when you left. I tried to settle down." he smiles softly, almost bitterly. "I was miserable. I... I can't live like that again. Mary knows that. She's very important to me, but she realizes that you're important, too, and that I can't help but to choose to help you over the prospect of a quiet night in."

"For how long?" Sherlock asks quietly.

"What?"

He elects to look at his hand instead of at John. The blood hasn't stopped flowing completely, but it has slowed. "How long will you tag along with me before you find other responsibilities that you think are more important? Before you start a _family_." He spits the word like a curse. "That takes precedent over 'friend,' doesn't it?" Social norms dictate that spouse trumps all other relationships. (Unless of course something goes wrong. But he's seen the dream couple, they're going to be fine for at least a few years.) His standing was doomed from the start.

John looks at him quietly for a few moments, gaze flickering between Sherlock's face and his sliced hand. He then reaches forward- but instead of trying for Sherlock's hand again, he picks up one of the shards of glass on the table.

It's not a large piece- less than an inch across. One corner of it is red where Sherlock had pulled it out of his palm.

Sherlock watches in confusion as John studies the piece of glass, and then, with careful concentration, presses the edge into his own right palm until beads of red form around it.

"What the hell are you doing?"

"Doing this the dramatic way. Figured this is the only way I'm going to get through to you. Now come on, give me your hand." He holds out his own bloody palm.

"John, this is stupid, now we have two lacerated hands to bandage. Why on Earth did you-"

"Give me your hand." He repeats in a low tone that bodes no room for argument.

Sherlock relents, his curiosity overpowering his sullenness.

John locks their hands firmly, and Sherlock can feel John's blood slick on his own palm.

"Sherlock, in three months, I am getting married to Mary Morstan." he says evenly. Sherlock narrows his eyes and tries to draw back again, but John holds him steady. "In three months, I am moving out of Baker Street."

"Yes" Sherlock sneers, "I believe we've been over that. That conversation went well, should we have it again?"

"Stop struggling. I am getting married, but that doesn't mean that I'm leaving you. You're not just my best friend. On the first night we met, I shot a man to save your life."

"You've shot men to save your army comrades. When's the last time you spoke to one of them?"

"You are determined to see the worst in this, aren't you?"

"I'm just being realistic."

"No, you're being difficult. Now look. Look at our hands." Sherlock complies. Drops of blood, both his and John's, are dripping onto the table. "I've had mates, Sherlock. I've had a good lot of friends. You're not my friend."

Sherlock tries to ignore the sinking feeling in his chest. Not John's friend. It shouldn't hurt to hear, but-

"Stop it. Stop whatever you're thinking there, and let me finish for once. You're not my friend. You're so much closer than that." Sherlock's breath catches again, and he almost doesn't dare to look at John. But when he does, John is returning his gaze steadily, dark blue eyes boring into his own. "If she's marrying me, she's got to understand that she's getting you as well. Because you're... shit, Sherlock, you're like a brother to me. You're obnoxious and immature and a right pain, but you're the brother I never had."

He lets go of Sherlock's hand, and raises his own to show his palm, smeared with red. Sherlock can't tell which blood is John's and which is his own. "Blood brothers. It's official, then."

"Is that what we just did?" Sherlock asks, just a little bemused.

"Yep. You're my brother now."

"You realize that it doesn't work like that-"

"Sherlock, if I can share a ring with Mary and make her family, then I can share a scar with you and make you family. Pretty sure it works just fine. Symbolism. It does wonders."

Sherlock blinks down at his hand. "I..." He... really has no idea what to say. For once in his life, he is struck truly speechless. "I have been reliably informed that I make a rather terrible brother." He manages at last.

"Yes, well, my track record's not too great either, if you ask Harry."

"I do try not to ask Harry anything." He manages a crooked grin to match John's.

"So there. Now you can stop worrying so much. Friends come and go, but family is forever, my mum used to say. Believe me, no matter how many times I try to shake myself of Harry, I can't seem to keep her away."

Sherlock lets out a light huff. "Oh, if only I could manage to be rid of Mycroft-" a pained look crosses his face- "half a moment! This still leaves me the youngest! Take it back! The last thing I need is another older sibling!"

John laughs. "No take-backs. You're stuck with me now. I'd promise to try not to be as much of a tit as Mycroft, but I think that's a given."

"You might want to watch your mouth. If you're my brother now, then by your logic so is Mycroft."

John pulls a face. "Well, maybe I didn't think this through quite thoroughly enough. But I suppose I'll manage. By the way, I'm assuming that you don't have HIV or anything, right?"

"Bit late to ask now."

They make an odd sight, do Sherlock and John, giggling there at the bloody kitchen table. And this time when John takes Sherlock's hand again to clean and bandage it, Sherlock lets him. He lets him because it's John's job to take care of him. And it'll stay John's job. Because he's gotten rather used to John Watson being a part of his life. Quite likes it in fact.

Oh, damn. Speaking of jobs- "I'm not going to get out of best man duty now, am I?"

"Good deduction. And I expect you to have Mary's name memorized by time the wedding rolls round."

Mary Morstan, soon-to-be Mary Watson. He can live with that. As long as John will always accompany him, he can live with that.

Only on one condition, however. Something that really should have been addressed right when this whole overly dramatic debacle had begun.

"John"

"Mm?"

"Tea."

_**I think that this could have been better, and I need to know how to fix my writing for future pieces. Cumbersome diction? Jerky pacing? Egregious usage of commas until all dialogue could be read by William Shatner? Tell me all! Happy reviews are like cake- sweet and delicious, but I'll get fat off of them! Critique is the meat and potatoes! Get scathing, get mean! Use your harsh Sherlock-voice! I won't be upset! Any sort of review will make me a better writer, which is what these are for!**_

_**Course, I won't say no to a happy review either! ;)**_


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